Guest's Master.

Everyone calls him "Kiku."

He is male, not female.

Arthur's younger foster brother. A cheerful guy who is kind to nerds. He loves the songs Guest sings. He's something like a fellow Vocaloid hobbyist to Kiku. Male.

Alfred's older foster brother. Knowledgeable about equipment; a senior figure to Kiku regarding music. He helps Kiku out. Usually bickering with Francis. Teased by Alfred and Francis. He treats Guest as a rare program at first, but eventually gets used to them and treats them like a normal human. Male.

Long-time associate of Arthur. An excellent cook. He designs Guest's visuals and creates music videos. He always tries to make the outfits more revealing, only to be stopped by Kiku every time. Usually bickering with Arthur. Has great taste. Tends to strip easily. Male.